KR20180024710A - White organic light emitting diode and display device applying the same - Google Patents

Abstract

The present invention relates to a white organic light emitting diode having a tandom structure with a long life and a low driving voltage, and a display device using the same. A white organic light emitting diode according to the present invention comprises: a first light emitting unit located between a first electrode and a second electrode; a second light emitting unit; and a third light emitting unit. The first and the third light emitting unit comprises a blue light emitting layer, and the second light emitting layer comprises a red light emitting layer and a yellow-green light emitting layer, and at least one layer of the above layers comprises a hole transporting host made of a compound shown below, wherein R1 to R3 are selected from hydrogen, heavy hydrogen, aromatic ring having carbon number of 1-6 or heterocyclic compounds.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic electroluminescent device and a display device using the organic electroluminescent device,

The present invention relates to an organic electroluminescent device and a display device using the organic electroluminescent device, and more particularly to a white organic electroluminescent device with a tandem structure capable of improving the lifetime of the device and a display device using the same.

Background Art Recently, interest in information displays has been increasing, and as demand for portable information media has increased, research and commercialization of lightweight thin display devices have been focused on.

The dual organic electroluminescent display device is superior to the liquid crystal display device in viewing angle, contrast ratio and the like by using an organic electroluminescent element of self-emission. Further, since the organic light emitting display does not require a separate light source, it is easy to implement a lightweight thin display device with less power consumption, and a flexible display device can be realized.

Such an organic electroluminescent device may be formed by stacking a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, an electron injecting layer, and a second electrode in this order on the first electrode, or stacking them in the reverse order. In this case, the electrode in contact with the hole injection layer is formed as an anode, and the electrode in contact with the electron injection layer is formed as a cathode.

The organic electroluminescent display device may have a structure in which a white organic electroluminescent device emits white light and the white light passes through a color filter to convert red, green, and blue light to display an image. In such an organic light emitting display device, a white organic electroluminescent device having a multi-stack structure including a plurality of light emitting layers is applied.

As the characteristics of the white organic electroluminescent device are better, the performance of the organic electroluminescent display device using the same is greatly improved. Therefore, it is a very important task to obtain a white organic electroluminescent device having excellent characteristics with a high driving efficiency, a long lifetime, and a low driving voltage in order to manufacture an organic light emitting display device having low power, long life, and high efficiency. It is actively being done.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a white organic light emitting device having a tandem structure with a high lifetime and a low driving voltage and a display device using the same.

According to an aspect of the present invention, there is provided a white organic electroluminescent device comprising: a first light emitting portion disposed on a first electrode and including a first blue light emitting layer; a first light emitting portion disposed on the first light emitting portion, Generating layer, a second light emitting portion located on the first charge generating layer, and a second electrode located on the second light emitting portion.

The second light emitting portion includes a red light emitting layer and a yellow-green light emitting layer, at least one of which includes a hole transport host based on the following compound.

Here, R 1 to R 3 may be selected from hydrogen, deuterium, aromatic rings having 1 to 6 carbon atoms, or heterocyclic compounds.

The yellow-green light emitting layer may be formed of two layers of first and second yellow-green light emitting layers. The ratio of the dopant of the first yellow-green light emitting layer in contact with the red light emitting layer is higher than the ratio of the second yellow-green light emitting layer in contact with the first yellow-green light emitting layer, wherein the dopant ratio of the first yellow- 10 to 50 wt%, and the dopant ratio of the second yellow-green light emitting layer is set within the range of 5 to 30 wt%.

When the red light emitting layer includes the hole transporting host, the ratio of the hole transporting host of the red light emitting layer has a value ranging from 10 to 50 wt%.

When the first yellow-green emitting layer comprises the hole transporting host, the ratio of the hole transporting host of the first yellow-green emitting layer has a value ranging from 15 to 55 wt%.

When the second yellow-green emitting layer comprises the hole transporting host, the ratio of the hole transporting host of the second yellow-green emitting layer has a value ranging from 40 to 80 wt%.

On the other hand, a green light emitting layer may be further disposed on the yellow-green light emitting layer, and at least one of the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer may include the hole transporting host.

When the yellow-green emitting layer includes the hole transporting host, the ratio of the hole transporting host of the yellow-green emitting layer is set in the range of 15 to 55 wt%. When the green emitting layer includes the hole transporting host , And the ratio of the hole transporting host of the green light emitting layer may be set in the range of 40 to 80 wt%.

In the structure including the yellow-green emitting layer and the green emitting layer, the ratio of the yellow-green dopant of the yellow-green emitting layer is higher than the ratio of the green dopant of the green emitting layer, and the ratio of the yellow- And the ratio of the green dopant is set within the range of 5 to 30 wt%.

Meanwhile, a second charge generation layer and a third light emitting portion may be provided between the second light emitting portion and the second electrode, and the third light emitting portion may include a second blue light emitting layer.

The white organic electroluminescent device according to the present invention to which the hole transporting host is applied has a high HOMO energy level of at least one of a red luminescent layer, a yellow-green luminescent layer and a green luminescent layer, Thereby improving the electron transporting characteristics from the electron transporting layer to each light emitting layer of the second light emitting portion.

Accordingly, the white organic electroluminescent device according to the present invention employing the hole transporting host is improved in both the hole transporting property and the electron transporting property, thereby increasing the recombination region of the electron-hole pairs in the light emitting layer, The lifetime of the device is increased.

In the present invention, when the yellow-green light emitting layer is divided into the first and second yellow-green light emitting layers and the dopant ratio is controlled to be different, the amount of electrons trapped in the second yellow-green light emitting layer having a relatively low dopant ratio And the first yellow-green light-emitting layer has a relatively high dopant ratio, so that the electrons from the second electron-transporting layer can reach the red light-emitting layer stably while maintaining the light-emitting efficiency of the yellow-green light-emitting layer. Accordingly, by adjusting the dopant ratios of the first and second yellow-green light emitting layers, the luminous efficiency increases and the driving voltage decreases.

The white organic electroluminescent device according to the present invention may include a green light emitting layer instead of the second yellow-green light emitting layer. In this case, the hole transporting host is applied to the green light emitting layer, and the proportion of the dopant is set lower than that of the yellow- Has the same effect as the above.

1A and 1B are schematic views for explaining a white organic electroluminescent device according to the present invention.
FIG. 2 is an exemplary view for explaining lifetime and efficiency improvement effect of the white organic electroluminescent device according to the present invention.
FIGS. 3 and 4 are graphs for explaining the lifetime increasing effect of the organic electroluminescent device according to the present invention.
5 is a cross-sectional view illustrating a schematic structure of each pixel included in the display panel according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, when it is determined that a detailed description of a technique or configuration related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. The component names used in the following description are selected in consideration of easiness of specification, and may be different from the parts names of actual products.

The term " on "or " on" of another element encompasses not only the element just above the other element layer but also intervening layers or other elements in the middle. On the other hand, an element or layer is referred to as being "tangential " to another element, indicating that no other element or layer is interposed.

1A and 1B are schematic views for explaining a white organic electroluminescent device according to the present invention.

1A, the white organic electroluminescent device according to the present invention includes a first light emitting portion 10 located on a first electrode 1 and including a first blue light emitting layer 13, A first charge generation layer 40 located on the first charge generation layer 40 and a second charge generation layer 40 located on the first charge generation layer 40; A third light emitting portion 30 located on the second charge generation layer 50 and including a second blue light emitting layer 32, And a second electrode (2) located on the portion (30).

The first electrode 1 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ZnO (Zinc Oxide), etc.) having a relatively large work function as an anode.

The first charge generating layer 40 includes a first N-type charge generating layer 41 and a first P-type charge generating layer 42. The first charge generating layer 40 may be formed in a laminated structure in which the first P-type charge generating layer 42 is located on the first N-type charge generating layer 41, but the present invention is not limited thereto. The first N-type charge generation layer 41 serves to inject electrons into the adjacent first light emitting portion 10 and the first P-type charge generation layer 42 serves to inject holes into the adjacent second light emitting portion 20 It plays a role of infusion.

The second charge generating layer 50 includes a second N-type charge generating layer 51 and a second P-type charge generating layer 52. The structure of the second charge generating layer 50 may be the same as that of the first charge generating layer 40, but is not limited thereto. The second n-type charge generation layer 51 serves to inject electrons into the second light emitting portion 20 and the second p-type charge generation layer 42 serves to inject electrons into the third light emitting portion 30 It plays a role.

The charge generating layers 40 and 50 may be formed using various organic materials having electron donor and acceptor characteristics.

For example, the P-type charge generation layers 42 and 52 may be formed by using hexaazatriphenylene-hexacarbonitrile (HAT-CN) (Dipyrazino [2,3- , 3, 6, 7, 10, 11-hexacar bonitrile) or a P-doped structure. The charge generating layers 40 and 50 may also be composed of a single layer such as the HAT-CN.

The first charge generation layer 40 controls the balance of the charge between the first light emitting portion 10 and the second light emitting portion 20 and the second charge generation layer 50 controls the balance of the charges between the second light emitting portion 20 And the third light emitting portion 30 is adjusted.

The first light emitting portion 10 includes a first hole transporting layer 11, a first blue light emitting layer 12 located on the first hole transporting layer 11, a first blue light emitting layer 12 located on the first blue light emitting layer 12, And an electron transport layer (13). The first hole transport layer 11, the first blue light emitting layer 12, and the electron transport layer 13 may be sequentially stacked, but the present invention is not limited thereto. For example, the first hole transporting layer 11 and the first electron transporting layer 13 may be formed as a single layer or a multilayer.

The first hole transport layer 11 may be formed in a multi-layered structure. The lower layer of the first hole transport layer 11, that is, a layer near the first electrode 1 is formed to include a material having a relatively high mobility, and an upper layer of the first hole transport layer 11, that is, a blue light emitting layer 12 are preferably formed to include a material having a relatively high triplet energy level (T1). The first hole transport layer 11 serves to smoothly supply holes supplied from the anode 1 to the first light emitting layer 12.

The first electron transporting layer 13 on the first blue light emitting layer 12 is formed in such a manner that electrons supplied from the first N-type charge generating layer 41 of the first charge generating layer 40 are smoothly transferred to the first blue light emitting layer 12 It is a role to deliver.

The third light emitting portion 30 includes a third hole transporting layer 31, a second blue light emitting layer 32 located on the third hole transporting layer 31, a third blue light emitting layer 32 located on the second blue light emitting layer 32, And an electron transporting layer (33). The third hole transport layer 31, the second blue emission layer 32, and the third electron transport layer 33 may be sequentially stacked, but the present invention is not limited thereto.

The first hole transport layer 11 serves to smoothly supply holes supplied from the anode 1 to the first light emitting layer 12 and the third electron transport layer 33 on the second blue light emitting layer 32 functions as a cathode 2) to the second blue light-emitting layer 32 smoothly.

The first and second blue light emitting layers 12 and 32 emit blue light with a light emitting layer containing a blue dopant and a host. At this time, the first and second blue light emitting layers 12 and 32 may be composed of a deep blue light emitting layer or a sky blue light emitting layer (sky blue). The peak wavelength region of the blue light emitting layer is determined within a range of about 440 nm to 480 nm. The first and second blue light-emitting layers 12 and 32 may emit fluorescence or phosphorescence. The first and second blue light-emitting layers 12 and 32 may include at least one host and at least one dopant. Specifically, at least one host material selected from the group consisting of an anthracene derivative, a pyrene derivative, and a perylene derivative may be doped with a blue dopant, but is not limited thereto.

The second light emitting portion 20 includes a red light emitting layer 21 and a yellow-green light emitting layer. Here, the yellow-green light-emitting layer may have a single layer structure or a multilayer structure, and may have a stacked structure in which the first yellow-green light-emitting layer 22 and the second yellow-green light-emitting layer 23 are sequentially in contact with each other.

The second electron-transporting layer 24 may be further disposed on the second yellow-green light-emitting layer 23. The second electron transport layer 24 may be formed in contact with the second yellow-green light emitting layer 23 and the second charge generating layer 50, but is not limited thereto. The second electron transport layer 24 serves to transfer electrons supplied from the second N-type charge generation layer 51 of the second charge generation layer 50 to the respective light emitting layers of the second light emitting portion 20.

At least one layer of the red luminescent layer 21, the first yellow-green luminescent layer 22 and the second yellow-green luminescent layer 23 is formed on the basis of the material of Formula 1, and the hole transporting host .

[Chemical Formula 1]

Here, the substituents R 1 to R 3 may be selected from among hydrogen, deuterium, aromatic rings having 1 to 6 carbon atoms, and heterocyclic compounds, but are not limited thereto.

Here, 'at least one layer' means that any one of the red light emitting layer 21, the first yellow-green light emitting layer 22, and the second yellow-green light emitting layer 23 includes the hole transporting host based on Formula 1 Or both layers or all of the layers may comprise a hole transport host based on the above Formula 1 material.

The red luminescent layer 21 may be a single host material based on a material selected from the group consisting of alpha -NPD, TCTA, TPD, TPB, TAC, m-TPEE, FTPD, NDA PP, TRP, PPD, Host material may be a co-deposited mixed host, but is not limited thereto.

On the other hand, the red light emitting layer 21 may include a hole transport host based on the Formula 1 material and a mixed host in which another host is co-deposited. The other host may be, but is not limited to, a host material based on a material selected from the aforementioned groups. When the white organic electroluminescent device includes the red light emitting layer 21, the efficiency and color of the white organic electroluminescent device are improved when the red organic electroluminescent device passes the red color filter to display red.

In the case where the red light emitting layer 21 includes a hole transporting host based on the Formula 1 material, when the ratio of the hole transporting host based on the Formula 1 material in the red light emitting layer 21 is within a range of 10 to 50 wt% 21) is maximized.

 The red luminescent layer 21 can emit fluorescence or phosphorescence.

The phosphorescent dopant material which can be used as a dopant of the red light emitting layer 21 may be a metal compound which forms a triple coordination with NN, NO or OO with an iridium (Ir) metal as a center. Specifically, the phosphorescent dopant is _{Ir (Piq) 3 (Tris (} 1-phenylisoquinoline) iridium (III)), Ir (piq) 2 (acac) (Bis (1-phenylisoquinoline) (acetylacetonate) iridiumIII)), Ir (btp _{) 2 (acac) (Bis)} 2-benzo [b] thiophen-2-yl-pyridine) (acetylacetonate) iridiumIII)), Ir (BT) 2 (acac) (Bis (2-phenylbenzothazolato) (acetylacetonate) iridiumIII)) And the like, but the present invention is not limited thereto.

The fluorescent dopant that can be used as a dopant of the red light emitting layer 21 is Rubrene (5,6,11,12-tetraphenylnaphthacene), DCJTB (4- (dicyanomethylene) -2-tert- , 7-tetramethyl juloidin-4-yl-vinyl) -4H pyran, and the like, but the present invention is not limited thereto.

The first yellow-green light-emitting layer 22 and the second yellow-green light-emitting layer 23 may include a mixed host in which a single host or at least one host is co-deposited, and at least one or more dopants. Specifically, the first and second yellow-green light emitting layers 22 and 23 may be formed by doping phosphorescent yellow-green dopants with a phosphorescent host material composed of a carbazole-based compound or a metal complex. The carbazole-based compound may include CBP (4,4'-bis (carbazol-9-yl) -biphenyl), CBP derivative, mCP (N, N'-dicarbazolyl-3,5benzene) , The metal complex may include znPBO (phenyloxazole) metal complex or ZnPBT (phenylthiazole) metal complex, and the like.

The doping ratio of the dopant of the first yellow-green light emitting layer 22 is higher than the doping ratio of the dopant of the second yellow-green light emitting layer 23. More specifically, the doping ratio of the dopant in the first yellow-green light emitting layer 22 is in the range of 10 to 50 wt%, the doping ratio of the dopant in the second yellow-green light emitting layer 23 is in the range of 3 to 35 wt% It is preferable to have a value within the range.

The dopant of the yellow-green light-emitting layer serves to trap electrons supplied from the second electron-transporting layer 24. Accordingly, when a yellow-green light emitting layer is formed as a single layer and has the same dopant ratio, the amount of electrons trapped in the yellow-green light emitting layer increases to fail to stably reach electrons up to the red light emitting layer 21, The efficiency of light emission of the light emitting diode decreases and the driving voltage rises.

On the other hand, when the dopant ratios of the first and second yellow-green light emitting layers 22 and 23 are adjusted to different values, the amount of electrons trapped in the second yellow-green light emitting layer 23 having a relatively low dopant ratio is reduced, The first yellow-green light-emitting layer 22 has a relatively high dopant ratio, so that the electrons from the second electron-transporting layer 24 can reach the red light-emitting layer 21 stably while maintaining the luminous efficiency of the yellow- have. Accordingly, by controlling the dopant ratios of the first and second yellow-green light emitting layers 22 and 23 differently, the luminous efficiency increases and the driving voltage decreases.

As noted above, the first yellow-green light-emitting layer 22 and the second yellow-green light-emitting layer 23 may comprise a hole transport host based on Formula 1 materials. In this case, the first yellow-green light-emitting layer 22 and the second yellow-green light-emitting layer 23 have a structure in which a hole transporting host based on the chemical formula 1 and a phosphorescent host material comprising the carbazole-based compound or metal complex are co- .

When the first yellow-green light-emitting layer 22 includes a hole transporting host based on the above-described Formula 1 material, the lifetime increase and effect of the first yellow light-emitting layer 22 are maximized when the ratio is in the range of 15 to 55 wt% . When the second yellow-green light-emitting layer 23 includes the hole transporting host based on Formula 1, if the ratio is in the range of 40 to 80 wt%, the lifetime of the second yellow-green light- The effect is maximized.

In the red light emitting layer 21, the first yellow-green light emitting layer 22, and the second yellow-green light emitting layer 23, the ratios thereof are different from each other for maximizing the lifetime of each light emitting layer. The reason for this is as follows.

First, since the red light emitting layer 21 is relatively close to the first P-type charge generating layer 42 of the first charge generating layer 40, a sufficient amount of holes are injected even if the proportion of the hole transporting host is not greatly increased On the other hand, when the ratio of the hole transporting host of the red light emitting layer 21 becomes excessively high, the influx of electrons supplied from the second N-type charge generating layer 52 or the second electrode 2 of the second charge generating layer 50 And in this case, the luminescent characteristics and lifetime are rather deteriorated. On the other hand, the second yellow-green light emitting layer 23 is relatively close to the second N-type charge generating layer 51 and relatively far away from the first P-type charge generating layer 42. Accordingly, although the injection of electrons is relatively smooth in the second yellow-green light emitting layer 23, it is necessary to further improve the hole transporting property, so that the lifetime increase effect can be enhanced by increasing the proportion of the hole transporting host.

Since the first yellow-green light-emitting layer 22 is located between the red light-emitting layer 21 and the second yellow-green light-emitting layer 23, the lifetime enhancement effect is maximized when the proportion of the intermediate hole-transport host is included.

On the other hand, as shown in FIG. 1B, the second yellow-green light-emitting layer 24 may be replaced with a green light-emitting layer 25. At this time, at least one host such as the first and second yellow-green light emitting layers 22 and 23 of the green light emitting layer 25 may include a co-deposited mixed host and at least one dopant. Specifically, the green light emitting layer 25 may be formed by doping a phosphorescent dopant with a phosphorescent host material comprising a carbazole-based compound or a metal complex. The carbazole-based compound may include CBP (4,4'-bis (carbazol-9-yl) -biphenyl), CBP derivative, mCP (N, N'-dicarbazolyl-3,5benzene) , And the metal complex may include znPBO (phenyloxazole) metal complex or ZnPBT (phenylthiazole) metal complex, but the present invention is not limited thereto.

As the green phosphorescent dopant, Ir (PPy) ₂ (acac), Ir (PPy) ₃ , GD48 of UDC, or the like may be used. The ratio of the green dopant of the green light emitting layer 25 is preferably lower than that of the yellow-green light emitting layer 22 because the phosphorescent dopant of the green light emitting layer 25 can also trap electrons . At this time, the doping ratio of the dopant in the yellow-green light emitting layer 22 is preferably in the range of 10 to 50 wt%, and the doping ratio of the dopant in the green light emitting layer 25 is preferably in the range of 3 to 35 wt%.

Likewise, the green light emitting layer 25 may comprise a hole transport host based on a Formula 1 material. At this time, the green light emitting layer 25 may be formed by co-deposition of a hole transporting host based on a compound of Formula 1 and a phosphorescent host material comprising the carbazole compound or a metal complex.

When the green light emitting layer 25 includes the hole transporting host based on the above Formula 1, the lifetime of the green light emitting layer 25 may be maximized when the green light emitting layer 25 is formed in the range of 40 to 80 wt%.

As described above, the tandem-type white organic electroluminescent device having the green light-emitting layer 25 on the yellow-green light-emitting layer 22 has the effect of improving the efficiency and color when displaying green through the green color filter .

A second hole transport layer (not shown) may be further disposed between the red light emitting layer 21 and the first charge generating layer 40. The second hole transport layer functions to supply the holes generated in the first P-type charge generation layer 42 of the first charge generation layer 40 to the red light emitting layer 21, and according to the design, the second hole transport layer The red light emitting layer 21 may also serve as a second hole transport layer.

The white organic light emitting device having the first light emitting portion 10, the second light emitting portion 20 and the third light emitting portion 30 has been described. However, according to the design of the white organic light emitting device, And the second charge generating layer 50 may be omitted. In this case, the white organic electroluminescent device according to the present invention is characterized in that the anode 1, the first light emitting portion 10, the first charge generating layer 40, the second light emitting portion 20, Can be stacked.

FIG. 2 is an exemplary view for explaining lifetime and efficiency improvement effect of the white organic electroluminescent device according to the present invention. 2 (a) shows the HOMO energy level and LUMO energy level of each host in the red luminescent layer, the green luminescent layer and the electron transport layer, which are typical host materials conventionally used.

In FIG. 2 (b), the same host material as the conventional host material is used for the red light emitting layer and the electron transporting layer, and the hole transporting host based on the compound of the formula 1 is used for the yellow-green light emitting layer. The HOMO energy level and the LUMO energy level of each host in the electron transport layer 222b and the electron transport layer 223.

The host has a HOMO energy level of -5.26 eV, a LUMO energy level of -2.17 eV, a HOMO energy level of the host of the yellow-green light emitting layer 222a of -5.32 eV, a LUMO energy level The level is -2.07 eV, the HOMO energy level of the electron transport layer 223 host is -6 eV, and the LUMO energy level is -3 eV.

On the other hand, the HOMO and LUMO energy levels of the host of the red light emitting layer 221 and the electron transporting layer 223 of FIG. 2 (b) are the same as those of FIG. 2 (a). The HOMO energy level of the yellow-green light emitting layer 222b host is -5.61 eV and the LUMO energy level is -2.28 eV, which is lower than the HOMO energy level of the yellow-green light emitting layer 222 shown in FIG. 2 (a) Has a HOMO energy level, and has a high LUMO energy level.

 Accordingly, the HOMO energy level of the yellow-green light-emitting layer 222 is significantly lower than the HOMO energy level of the adjacent red light-emitting layer, and the hole transporting property from the red light-emitting layer 21 to the yellow-green light- .

2 (a), the LUMO energy level of the host of the yellow-green emitting layer 222a is higher than the LUMO energy level of the host of the electron transporting layer 223 and the LUMO energy level of the host of the red emitting layer 221. [ 2 (b), the LUMO energy level of the host of the yellow-green emitting layer 222b is higher than the LUMO energy level of the host of the adjacent electron transporting layer 223 and lower than the LUMO energy level of the host of the red emitting layer 221. The electron transporting property from the electron transporting layer 223 to the red light emitting layer 221 through the yellow-green light emitting layer 222b is greatly improved.

In other words, the white organic electroluminescent device to which the hole transporting host based on the compound 1 according to the present invention is applied has improved hole transporting properties and electron transporting properties, and as a result, the recombination region of electron- The efficiency is improved and the lifetime of the device is increased.

FIGS. 3 and 4 are graphs for explaining the lifetime increasing effect of the organic electroluminescent device according to the present invention. 3 is a graph for explaining the lifetime increasing effect of the white organic light emitting device in which the second light emitting portion 20 is laminated in the order of the red light emitting layer, the first yellow-green light emitting layer, and the second yellow-green light emitting layer. 4 is a graph for explaining the lifetime increase of the white organic light emitting device in which the second light emitting portion 20 is laminated in the order of red, light emitting layer, yellow-green light emitting layer and green light emitting layer.

3 and 4, the white organic electroluminescent device according to the comparative example is based on the prior art. In the white organic electroluminescent device according to the embodiment, the red light emitting layer, the yellow-green light emitting layer, Hole transport host.

The white organic electroluminescent device of FIG. 3 has a red luminance lifetime increased by about 80% and a green luminance lifetime increased by about 43% as compared with the prior art.

It can be seen that the white organic electroluminescent device of FIG. 4 has a red luminance lifetime of about 15% and a green luminance lifetime of about 26% as compared with the conventional one.

As described above, the white organic electroluminescent device to which the hole transporting host based on the formula 1 material is applied according to the present invention has an effect of significantly increasing the red and green luminance lifetime compared to the conventional one.

5 is a cross-sectional view illustrating a schematic structure of each pixel included in the display panel according to the present invention.

The driving transistor TR2 is formed on the substrate 100 and the buffer layer 101 as shown in Fig. 5 and includes a semiconductor layer 104 including a source region 109a and a drain region 109b on both sides, A gate insulating film 106 covering the semiconductor layer 104, a gate electrode 102 located above the gate insulating film 106 corresponding to the semiconductor layer 104, and a substrate including the gate electrode 102 A first passivation layer 112 covering the source and drain regions 109a and 109b and covering the source and drain regions 109a and 109b on both sides of the semiconductor layer 104; And a source electrode 110 and a drain electrode 108 connected to the source / drain regions 109a and 109b.

 The second passivation layer 114 and the third passivation layer 116 are located on the driving transistor TR2. On the third passivation layer 116, the organic electroluminescent device according to the present invention is located. The organic electroluminescent device includes a bank insulating film 124 on which a first electrode 1 and an opening 133 for exposing the first electrode 1 are formed, a spacer 126 located on the bank insulating film 124, An organic layer 118 including a light emitting layer formed on the first electrode 1 exposed through the opening 133 and a second electrode 2 formed on the organic layer 118.

The first protective layer 112 includes a contact hole exposing the drain electrode 108 and the first electrode 1 is connected to the drain electrode 108 of the thin film transistor through the contact hole.

At this time, the substrate 100 is a flexible glass or polymer substrate, and the light emitting display panel according to the present invention can be manufactured as a flexible display or a foldable display. In this case, the light emitting display panel according to the present invention includes at least one folding area in the display area, and the entire display area may be bent.

The organic layer 118 is configured to include the organic electroluminescent device according to the present invention. The organic layer 118 is applied to the structure of the white organic electroluminescent device according to the present invention. That is, the first light emitting portion 10, the first charge generating layer 40 and the second light emitting portion 20 according to the present invention are sequentially stacked between the first electrode 1 and the second electrode 2 The first light emitting portion 10, the first charge generating layer 40, the second light emitting portion 20, the second charge generating layer 50 and the third light emitting portion 30 may be sequentially stacked.

The barrier layer 130 is located on the second electrode 2. The barrier layer 130 has a structure in which at least one of the inorganic film 127 and the organic film 129 is stacked and crossed.

In the organic light emitting display device using the white organic electroluminescent device according to the second embodiment, a color filter 135 is disposed in a region corresponding to the opening 133 on the second passivation layer 114. The color filter 135 converts the white light emitted from the white organic electroluminescence device to red, green and blue.

The organic electroluminescent display device using the white organic electroluminescent device and the color filter 135 may be formed by depositing red, green, and blue organic electroluminescent devices independently on each pixel, The light emitting portions 30, 50, and 70 are formed on the entire pixels. Accordingly, an organic light emitting display device using a white organic electroluminescent device can form an organic layer 118 without a mask, but also has an effect of increasing the size, lifetime, and power consumption.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

1: first electrode 2: second electrode
10: first light emitting portion 20: second light emitting portion
30: Third light emitting portion 40: First charge generating layer
50: second charge generating layer 11: first hole transporting layer
12: first blue light emitting layer 13: first electron transporting layer
41: first N-type charge generation layer 42: first P-type charge generation layer
21: red luminescent layer 22: first yellow-green luminescent layer
23: second yellow-green light-emitting layer 24: second electron-transporting layer
51: second N-type charge generation layer 52: second P-type charge generation layer
31: third hole transporting layer 32: third blue light emitting layer
33: third electron transport layer 25: green light emitting layer
100: substrate 101: buffer layer
102: gate electrode 104: semiconductor layer 109a, 109b: source / drain region 106: gate insulating film
108: drain electrode 110: drain electrode
114: second protective layer 116: third protective layer
133: opening 118: organic layer
135: Color filter 130: Barrier layer

Claims (16)

A first light emitting portion located on the first electrode and including a first blue light emitting layer,
A first charge generation layer located on the first light emitting portion,
A second light emitting portion located on the first charge generating layer, and
And a second electrode located on the second light emitting portion,
The second light-
A red light emitting layer located on the first charge generation layer,
And a yellow-green light-emitting layer positioned on the red light-emitting layer,
Wherein at least one of the red light emitting layer and the yellow-green light emitting layer comprises a hole transporting host based on the following compound.

(Wherein R1 to R3 are selected from hydrogen, deuterium, aromatic rings having 1 to 6 carbon atoms, or heterocyclic compounds). The method according to claim 1,
The yellow-green light-
A first yellow-green light-emitting layer in contact with the red light-emitting layer, and
And a second yellow-green light-emitting layer in contact with the first yellow-green light-emitting layer. 3. The method of claim 2,
And the ratio of the dopant of the first yellow-green light emitting layer is higher than that of the second yellow-green light emitting layer. The method of claim 3,
The ratio of the dopant of the first yellow-green light emitting layer is set within the range of 10 to 50 wt,
And the ratio of the dopant of the second yellow-green light emitting layer is set within a range of 5 to 30 wt%. The method according to claim 1,
Wherein the red light emitting layer comprises the hole transporting host, wherein the ratio of the hole transporting host of the red light emitting layer is 10 to 50 wt%. 3. The method of claim 2,
Wherein the first yellow-green emitting layer comprises the hole transporting host, wherein the ratio of the hole transporting host of the first yellow-green emitting layer is 15-55 wt%. 3. The method of claim 2,
Wherein the second yellow-green emitting layer comprises the hole transporting host, wherein the ratio of the hole transporting host of the second yellow-green emitting layer is 40-80 wt%. The method according to claim 1,
A second charge generation layer located on the yellow-green light emitting layer, and
And a third light emitting portion located between the second charge generation layer and the second electrode and including a second blue light emitting layer. A first light emitting portion located on the first electrode and including a first blue light emitting layer,
A first charge generation layer located on the first light emitting portion,
A second light emitting portion located on the first charge generating layer, and
And a second electrode located on the second light emitting portion,
The second light-
A red light emitting layer located on the first charge generation layer,
A yellow-green light-emitting layer positioned on the red light-emitting layer, and
And a green light emitting layer disposed on the yellow-green light emitting layer,
Wherein at least one of the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer comprises a hole transporting host based on the following compound.

(Wherein R1 to R3 are selected from hydrogen, deuterium, aromatic rings having 1 to 6 carbon atoms, or heterocyclic compounds). 10. The method of claim 9,
Wherein the red light emitting layer comprises the hole transporting host, wherein the ratio of the hole transporting host of the red light emitting layer is 10 to 50 wt%. 10. The method of claim 9,
Wherein the yellow-green emitting layer comprises the hole transporting host, wherein the ratio of the hole transporting host of the yellow-green emitting layer is 15-55 wt%. 10. The method of claim 9,
The green light emitting layer includes the hole transporting host, wherein the ratio of the hole transporting host of the green light emitting layer is 40 to 80 wt%. 10. The method of claim 9,
And the ratio of the yellow-green dopant of the yellow-green emitting layer is higher than the ratio of the green dopant of the green emitting layer. 13. The method of claim 12,
The ratio of the yellow-green dopant of the yellow-green light emitting layer is set within the range of 10 to 50 wt,
Wherein a ratio of a green dopant of the green light emitting layer is set within a range of 5 to 30 wt%. 10. The method of claim 9,
A second charge generation layer disposed on the green light emitting layer, and
And a third light emitting portion located between the second charge generation layer and the second electrode and including a second blue light emitting layer. A thin film transistor positioned on a substrate,
A first protective layer positioned to cover the thin film transistor,
A color filter layer disposed on the protective layer,
A second protective layer located on the color filter layer,
A contact hole exposing a drain electrode of the thin film transistor;
15. The organic electroluminescent display device according to any one of claims 1 to 15, wherein the white organic electroluminescent device is disposed on the second passivation layer and connected to the drain electrode of the thin film transistor through the contact hole.

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